Lycoptera is a genus of fish that lived from the late Jurassic to Cretaceous periods in present-day China, Korea, Mongolia and Siberia. It is known from abundant fossils representing sixteen species, which serve as important index fossil used to date geologic formations in China. Along with the genus Peipiaosteus, Lycoptera has been considered a defining member of the Jehol Biota, a prehistoric ecosystem famous for its early birds and feathered dinosaurs, which flourished for 20 million years during the Early Cretaceous.
Lycoptera species were small freshwater fish. Most species fed on plankton, and had numerous tiny teeth. A few species like L. gansuensis, L. muroii, and L. sinensis had larger teeth and probably fed on small insects and their larvae.
Many specimens preserve minute details and impressions of soft tissues. Lycoptera was covered in tiny oval scales about 1.2 millimeters across, and, in life, would have had a superficial resemblance to the Common minnow.
Lycoptera fossils are commonly found in large groups, buried together quickly in fine lake sediments. This probably indicates that they were gregarious in life, congregating in shoals.